Operating machines, such as hydraulic excavators and cranes, are publicly known. These operating machines can perform various work by moving operating devices, such as shovels and cranes. Such an operating machine includes a lower body configured to be able to travel. A revolving super structure is provided on the lower body. The operating device, such as the shovel or the crane, is attached to the revolving super structure. The revolving super structure is configured to be turnable relative to the lower body and can change a direction of the operating device. The revolving super structure configured as above is configured to be able to be turned by a drive control system.
One example of the drive control system is disclosed in PTL 1. The drive control system of PTL 1 includes an electric motor and an oil-pressure motor. The electric motor and the oil-pressure motor cooperate with each other to turn the revolving super structure. An output torque of the electric motor and an output torque of the oil-pressure motor are controlled by a control device. When turning the revolving super structure, the control device calculates torque (i.e., maximum torque) which can be output from the electric motor. Then, the control device causes the electric motor to output the maximum torque. Further, the control device causes the oil-pressure motor to output residual torque. Since the oil-pressure motor and the electric motor cooperate with each other to turn the revolving super structure as above, energy necessary to drive the oil-pressure motor is reduced in the drive control system of PTL 1.